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Structure of hydridocarboxylatotris(triphenylphosphine)ruthenium(II) complexes in solution
INORG. NUCL. CHEM. LETTERS Vol. 12, pp. 661-663, 1976. Pergamon Press. Printed inGreat Britain.
STRUCTURE OF HYDRIDOCARBOXYLATOTRIS(TRIPIIENYLPHOS~INE)RUTHENIU~(II) COMPLEXES IN SOLUTION. Alwyn Spencer. Monsanto Research S.A., EggbGhlstrasse Switzerland.
56, CH-8050 Z~irich,
(Received 20 May 1976)
Introduction. During further studies on phosphine-carboxylate have had cause to re-examine
the n.m.r,
RuH(CO2R)(PPhs) 3. These complexes have been reported catalysts for the homogeneous
complexes of ruthenium, we
spectra of complexes of the type
hydrogenation
to be highly efficient
of 1-alkenes
(I). The IH n.m.r.
spectra of the complexes for a wide range of R groups were also stated to show symmetrical
quartet resonances
for the hydride ligands, which was interpreted
as being indicative of the hyaride coupling to three equivalent cis-phosphorus nuclei.
The crystal structure of the acetato-complex
(2) shows it to possess
meridonally arranged phosphines with the hydride mutually cis to them, and a bidentate acetate group occupying the fifth and sixth coordination above-mentioned coordination conclusion
n.m.r,
spectra therefore required a rearrangement
spheres of the complexes in solution.
is incorrect,
sites. The of the
It is shown here that this
and arose from a lack of resolving power of the
spectrometer used in the initial study . The 51p n.m.r, and solution infrared spectra of the complexes, not previously reported, were also studied. Experimental. The acetate, RuH(CI)(PPhs)3,
propionate and n-butyrate complexes,
were prepared by the literature methods from RuCI2(PPh~) ~ ..
and all gave correct elemental analyses n.m.r,
(~[H Microlabor,
spectra were recorded in deuterochloroform
Bruker WP60 spectrometer. sealed under vacuum. 21 instrument.
and the complex
ZUrich).
(3,4), ~51 H and P
solution at 25 ° using a
Samples were prepared by vacuum-line
Infra-red
i
techniques and
spectra were recorded on a Perkin-Elmer Model
The solutions were prepared and introduced to the sample cell
under an argon atmosphere. Results and Discussion. The IH and 51p n.m.r,
spectra of the complexes are summarised in Tables i 661
Hydridocarboxylatotris (triphenylphosphine) ruthenium (II)
662
and 2. The hydride spectra of all three carboxylate complexes appear as two overlapping triplets. The coupling constants of the hydride to the two equivalent phosphines (JP2_H) and to the remaining phosphine (JD _H ) differ by only 1.4 to 2.2 Hz. This causes the inner intensity 1 peak of each triplet to lie at the above separation from the intensity 2 peak of the other triplet, and the previous interpretation of the signal as a quartet was clearly due to inadequate resolving power of the spectrometer used.
Table i. IH n.m.r. Spectra of RuH(X)(PPhs) 5 Complexes in CDCI 5 Solution. X
6 (ppm)
Cl
JP-!t
JP2-H
JP1-H (Hz)
25.85
+17.79
C02Me
+18.68
27.0
28.4
CO2Pr
+18.76
26.1
28.5
CO2Bu n
+18.7!9
26.2
27.7
tel. to tms.
The proton-decoupled 31p spectra (Table 2) of the carboxylate complexes all exhibit a doublet of intensity 2, and to low field a triplet of intensity i, confirming the phosphine inequivalence shown in the IH spectra. In view of this the spectrmm of the related complex R~{(CI)(PPh3) 3 was also recorded. The IH spectrum showed a symmetrical quartet resonance for the hydride, and a single line was observed in the 51p spectrmm. The earlier results are thus confirmed in this case. No evidence for phosphine-dissociation was observed in any of the n.m.r, spectra.
Table 2. 51p n.m.r. Spectra of RuH(X)(PPhs) 3 Complexes in CDCI 3 Solution.
X CI
6
6p2"
@p1 (ppm) gpp(HZ)
-27.55
C02Me
-43.99
-77.83
28.17
C02Pr
-44.28
-77.91
26.59
C02Bun
-43.99
-75.79
28.12
rel. to HsPO 4.
Hydridocarboxylatotris (triphenylphosphine) ruthenium (II)
663
The solution infra-red spectra of the complexes have not been previously recorded. We have obtained the spectra in argon-saturated chloroform solutions over the range 1350-1700 cm -I. The weak absorptions of the solvent in this region were easily compensated for. In addition to phosphine bands, the symmetric and antisymmetric carboxylate stretches are seen at ca. 1450 and 1550 cm -I. For all three complexes the spectra were identical with the solid-state (KBr disc) spectra. It is therefore clear that no change in the mode of coordination of the carboxylate groups occurs on dissolving. This, together with the n.m.r, results, indicates that the six-coordinate meridonal phosphine structure found in the crystal (2) persists in solution. Acknowledgement. The author wishes to thank ~r. F. Bangerter for recording the n.m.r, spectra.
References, i.
D. ROSE, J.D. GILBERT, R.Po RICHARDSON and G. WILKINSON.
J. Chem. Soc. A.
2610, (1969). 2.
A.C. SKAPSKI and F.A. STEPHENS.
3.
R.W.
4.
R.A. SCHUNN and E.~. WONCHOBA.
J.C.S. Dalton. 590, (1974).
MITCHELL, A. SPENCER and C. WILKINSON.
J.C.S. Dalton. 846, (]973).
Inorg. Synth. 151, 13, (1972).
STRUCTURE OF HYDRIDOCARBOXYLATOTRIS(TRIPIIENYLPHOS~INE)RUTHENIU~(II) COMPLEXES IN SOLUTION. Alwyn Spencer. Monsanto Research S.A., EggbGhlstrasse Switzerland.
56, CH-8050 Z~irich,
(Received 20 May 1976)
Introduction. During further studies on phosphine-carboxylate have had cause to re-examine
the n.m.r,
RuH(CO2R)(PPhs) 3. These complexes have been reported catalysts for the homogeneous
complexes of ruthenium, we
spectra of complexes of the type
hydrogenation
to be highly efficient
of 1-alkenes
(I). The IH n.m.r.
spectra of the complexes for a wide range of R groups were also stated to show symmetrical
quartet resonances
for the hydride ligands, which was interpreted
as being indicative of the hyaride coupling to three equivalent cis-phosphorus nuclei.
The crystal structure of the acetato-complex
(2) shows it to possess
meridonally arranged phosphines with the hydride mutually cis to them, and a bidentate acetate group occupying the fifth and sixth coordination above-mentioned coordination conclusion
n.m.r,
spectra therefore required a rearrangement
spheres of the complexes in solution.
is incorrect,
sites. The of the
It is shown here that this
and arose from a lack of resolving power of the
spectrometer used in the initial study . The 51p n.m.r, and solution infrared spectra of the complexes, not previously reported, were also studied. Experimental. The acetate, RuH(CI)(PPhs)3,
propionate and n-butyrate complexes,
were prepared by the literature methods from RuCI2(PPh~) ~ ..
and all gave correct elemental analyses n.m.r,
(~[H Microlabor,
spectra were recorded in deuterochloroform
Bruker WP60 spectrometer. sealed under vacuum. 21 instrument.
and the complex
ZUrich).
(3,4), ~51 H and P
solution at 25 ° using a
Samples were prepared by vacuum-line
Infra-red
i
techniques and
spectra were recorded on a Perkin-Elmer Model
The solutions were prepared and introduced to the sample cell
under an argon atmosphere. Results and Discussion. The IH and 51p n.m.r,
spectra of the complexes are summarised in Tables i 661
Hydridocarboxylatotris (triphenylphosphine) ruthenium (II)
662
and 2. The hydride spectra of all three carboxylate complexes appear as two overlapping triplets. The coupling constants of the hydride to the two equivalent phosphines (JP2_H) and to the remaining phosphine (JD _H ) differ by only 1.4 to 2.2 Hz. This causes the inner intensity 1 peak of each triplet to lie at the above separation from the intensity 2 peak of the other triplet, and the previous interpretation of the signal as a quartet was clearly due to inadequate resolving power of the spectrometer used.
Table i. IH n.m.r. Spectra of RuH(X)(PPhs) 5 Complexes in CDCI 5 Solution. X
6 (ppm)
Cl
JP-!t
JP2-H
JP1-H (Hz)
25.85
+17.79
C02Me
+18.68
27.0
28.4
CO2Pr
+18.76
26.1
28.5
CO2Bu n
+18.7!9
26.2
27.7
tel. to tms.
The proton-decoupled 31p spectra (Table 2) of the carboxylate complexes all exhibit a doublet of intensity 2, and to low field a triplet of intensity i, confirming the phosphine inequivalence shown in the IH spectra. In view of this the spectrmm of the related complex R~{(CI)(PPh3) 3 was also recorded. The IH spectrum showed a symmetrical quartet resonance for the hydride, and a single line was observed in the 51p spectrmm. The earlier results are thus confirmed in this case. No evidence for phosphine-dissociation was observed in any of the n.m.r, spectra.
Table 2. 51p n.m.r. Spectra of RuH(X)(PPhs) 3 Complexes in CDCI 3 Solution.
X CI
6
6p2"
@p1 (ppm) gpp(HZ)
-27.55
C02Me
-43.99
-77.83
28.17
C02Pr
-44.28
-77.91
26.59
C02Bun
-43.99
-75.79
28.12
rel. to HsPO 4.
Hydridocarboxylatotris (triphenylphosphine) ruthenium (II)
663
The solution infra-red spectra of the complexes have not been previously recorded. We have obtained the spectra in argon-saturated chloroform solutions over the range 1350-1700 cm -I. The weak absorptions of the solvent in this region were easily compensated for. In addition to phosphine bands, the symmetric and antisymmetric carboxylate stretches are seen at ca. 1450 and 1550 cm -I. For all three complexes the spectra were identical with the solid-state (KBr disc) spectra. It is therefore clear that no change in the mode of coordination of the carboxylate groups occurs on dissolving. This, together with the n.m.r, results, indicates that the six-coordinate meridonal phosphine structure found in the crystal (2) persists in solution. Acknowledgement. The author wishes to thank ~r. F. Bangerter for recording the n.m.r, spectra.
References, i.
D. ROSE, J.D. GILBERT, R.Po RICHARDSON and G. WILKINSON.
J. Chem. Soc. A.
2610, (1969). 2.
A.C. SKAPSKI and F.A. STEPHENS.
3.
R.W.
4.
R.A. SCHUNN and E.~. WONCHOBA.
J.C.S. Dalton. 590, (1974).
MITCHELL, A. SPENCER and C. WILKINSON.
J.C.S. Dalton. 846, (]973).
Inorg. Synth. 151, 13, (1972).